Remotely controlled welding machine

ABSTRACT

The present invention is directed to a remotely controlled welding machine. A remote control uses the welding circuit to transfer information to a welding power source. The information to be communicated to the power source includes welding power source output command information (amperage/voltage control), welding circuit on/off information (power source output contactor control), and power source mode control (constant voltage/constant current). A transmitter transmits the desired welding operational parameters to a receiver disposed in the power source. The transmitter is constructed to use only a small amount of power which, preferably, is supplied by one or two low voltage replaceable and/or rechargeable batteries. Additionally, an open circuit voltage is not created between the power source and an electrode holder when an arc is not present.

BACKGROUND OF INVENTION

The present invention relates generally to welding machines and, moreparticularly, to a method and apparatus of communicating control signalsto a welding power source from a remote location. Specifically, theinvention relates to a power source whose operation is governed bycontrol signals provided by a controller in response to command signalsreceived across the weld cables connecting a wire feeder to the powersource. In this regard, a voltage potential is not created between thesecondary output of the power source and the wire feeder until apower-up command is transmitted to the receiver across the weld cablesby the transmitter.

MIG welding, formerly known as Gas Metal Arc Welding (GMAW), combinesthe techniques and advantages of TIG welding's inert gas shielding witha continuous, consumable wire electrode. An electrical arc is createdbetween the continuous, consumable wire electrode and a workpiece. Assuch, the consumable wire functions as the electrode in the weld circuitas well as the source of filler metal. MIG welding is a relativelysimple process that allows an operator to concentrate on arc control.MIG welding may be used to weld most commercial metals and alloysincluding steel, aluminum, and stainless steel. Moreover, the travelspeed and the deposition rates in MIG welding may be much higher thanthose typically associated with either Gas Tungsten Arc Welding (TIG) orShielded Metal Arc Welding (stick) thereby making MIG welding a moreefficient welding process. Additionally, by continuously feeding theconsumable wire to the weld, electrode changing is minimized and assuch, weld effects caused by interruptions in the welding process arereduced. The MIG welding process also produces very little or no slag,the arc and weld pool are clearly visible during welding, and post-weldclean-up is typically minimized. Another advantage of MIG welding isthat it can be done in most positions which can be an asset formanufacturing and repair work where vertical or overhead welding may berequired.

A wire feeder is operationally connected to the power source and isdesigned to deliver consumable wire to a weld. To further enhance theoperability of the wire feeder of a MIG welding system, known weldingsystems have connected the power source and the wire feeder to oneanother such that control signals defining the operational parameters ofthe power source are transmitted or fed back from the wire feeder to thepower source, generally referred to as remote control.

One type of remote control device is used to regulate the outputvoltage, current, and switch the welding power source output ON and OFFas well as change the power source mode via a pendant that connects tothe power source by a multi-conductor cable. The solution isschematically illustrated in FIG. 1A. A wire feeder 2A is connected to apower source 4A by a control cable 6A that includes a 14-pin connector.The cable 6A used to transmit operational information to, and in somecases from the power source, may incorporate 2 to 14 conductorsdepending on how many functions are to be controlled. Separatelyconnected between the power source 4A and wire feeder 2A is a highvoltage weld cable 8A that delivers power to the wire feeder and createsa voltage potential between an electrode and a workpiece.

A significant drawback to this cable-based control is that the controlcable is typically fragile relative to the welding cables designed tocarry high currents at high voltages. Welding machines are commonly usedat construction sites or shipyards where it is not uncommon for thewelding machines to be periodically relocated or surrounded by othermobile heavy equipment operating in the same area. As such, the remotecontrol cable can become damaged by being crushed or snagged fromcontact with surrounding machines and/or traffic. This can cause damageto the wire feeder and/or the welding power source if internal powerconductors become shorted to signal leads that are connected tosensitive signal level circuitry.

One known system is a voltage following or voltage sensed wire feederhaving an internal contactor. This solution is schematically shown inFIG. 1B. As shown, this system includes a wire feeder 2B that receivesits electrical power from the voltage present in the welding circuit.The wire feeder is connected to a power source 4B via a weld cable 8B.With this system, the operator sets a desired welding current at thepower source 4B and the wire feeder 2B regulates the arc voltage byincreasing the rate wire feed is fed if the arc voltage increases andreduces the wire feed rate if the arc voltage decreases in order tomaintain a constant arc voltage. One disadvantage of this system is thatthe operator has no convenient way to adjust the output of the weldingpower source to compensate for changes in workpiece thickness and/or fitup. The operator may call another person more conveniently located tothe power source with a radio or some other means of communication tomake the adjustment; however, if the operator is working alone, s/hemust return to the power source to make the necessary adjustments.Another disadvantage of this system is that it requires the presence ofa high current DC contactor to de-energize the welding circuit at thewire feeder. These contactors are large, heavy, costly, and requireperiodic maintenance to ensure proper and continual operation. Thelocation of the secondary contactor in the remotely located wire feederalso requires that the welding circuit from the welding power source tothe wire feeder remain energized even when not welding so that power isavailable to the wire feeder and welding arc when the gun trigger isactivated. Accordingly, an open circuit voltage remains present acrossthe weld cables. The weld cables, however, can become damaged at aworksite resulting in an unwanted arc being formed between an exposedportion of the cable and an unexpectant ground.

Referring now to FIG. 1C, another remote controlled system includes aradio transmitter type remote control. This approach has severaldisadvantages. First, electric arc welding can create radio frequencyinterference that negatively affects the communication between atransceiver 9A of the wire feeder 2C and the transceiver 9B of the powersource 4C. Second, if the system is used inside metal structures such astanks, ships, or large aircraft, the radio link can be lost due to theshielding effect of the metallic surroundings. Third, if multiplewelding stations use a radio link for remote control, each control loopwould require a separate security code to prevent cross-talk ormis-transmission of control signals to the wrong welding machine.

It is therefore desirable to design a remotely controlled weldingmachine that receives command signals from a wire feeder across a weldcables such that an open circuit voltage is not created between thesecondary output of a power source and the wire feeder when the wirefeeder is not supplying consumable wire to a weld. It would also bedesirable to design a wire feeder absent a separate contactor assembly.

BRIEF DESCRIPTION OF INVENTION

The present invention is directed to a remotely controlled weldingmachine that overcomes the aforementioned drawbacks. A remote controluses the welding circuit to transfer information to a welding powersource. The information to be communicated to the power source includeswelding power source output command information (amperage/voltagecontrol), welding circuit on/off information (power source outputcontactor control), and power source mode control (constantvoltage/constant current). A transmitter transmits the desired weldingoperational parameters to a receiver disposed in the power source. Thetransmitter is constructed to use only a small amount of power which,preferably, is supplied by one or two low voltage replaceable and/orrechargeable batteries. Additionally, an open circuit voltage is notcreated between the power source and an electrode holder when an arc isnot present.

Therefore, in accordance with one aspect of the present invention, awelding system includes a power source having a controller to regulatewelding operation. An electrode holder having a trigger is configured tohold an electrode in relative proximity to a workpiece such that awelding arc is created between the electrode and the workpiece. Thesystem also includes a transmitter configured to detect activation ofthe trigger and, responsive thereto, transmit a signal indicative ofdesired welding operation through weld cables. A receiver is providedremotely from the transmitter and is configured to receive the signaland instruct the controller of the power source according to the desiredwelding operation.

In accordance with another aspect of the present invention, a weldingsystem includes a power source configured to condition raw power andsupply a power usable during a welding process. A wire feeder isconfigured to receive the power from the power source and supply aconsumable electrode to a weld. The wire feeder includes a torchconnected thereto and a transmitter configured to detect activation ofthe torch and transmit a signal to a receiver of the power sourceindicating activation of the torch. The welding system further includesa welding cable connecting the power source and the wire feeder to oneanother such that the signal is transmittable thereacross from thetransmitter to the receiver. The system is constructed such that avoltage is not created across the weld cable until the transmittertransmits a signal to the receiver signaling that the torch has beenactivated.

According to another aspect of the present invention, a method ofremotely controlling a power source for a welder includes the step ofdetecting activation of a triggering mechanism of a welding-type torchto initiate a welding-type process. The method further includes the stepof transmitting a signal indicative of desired operational parameters ofthe power source through weld cables connected to the power source and aworkpiece, automatically upon activation of the triggering mechanism.The transmitted signal is then received remotely from the triggeringmechanism whereupon the power source is controlled in accordance withdata embodied in the signal transmitted through the weld cables.

In accordance with yet a further aspect of the present invention, a kitto retrofit a welder and wire feeder system is provided. The kitincludes a transmitter to be disposed within a wire feeder andconfigured to detect activation of a welding torch. The kit alsoincludes a receiver to be disposed within a power source andelectrically connected to the transmitter through the weld cables. Acontroller is provided to regulate operation of the power source suchthan an open circuit voltage is not created across the weld cables untilan energized secondary voltage command signal is received by thereceiver from the transmitter.

Various other features, objects and advantages of the present inventionwill be made apparent from the following detailed description and thedrawings.

BRIEF DESCRIPTION OF DRAWINGS

The drawings illustrate one preferred embodiment presently contemplatedfor carrying out the invention.

In the drawings:

FIGS. 1A-1C are schematic block diagrams illustrating examples of knownremotely controlled welding and wire feeder systems.

FIG. 2 is a pictorial view of a welding system in accordance with oneaspect of the present invention.

FIG. 3 is a schematic of the welding system illustrated in FIG. 2.

FIG. 4 is a schematic diagram of operational circuitry of a transmitterin accordance with one aspect of the present invention.

FIG. 5 is a schematic diagram of operational circuitry of a receiver inaccordance with one aspect of the present invention.

DETAILED DESCRIPTION

The present invention will be described with respect to regulation of apower source and wire feeder of a MIG welding system based on feedbackprovided from a transmitter remote from the power source to a receiverincorporated within the power source. However, the present invention isequivalently applicable with regulating power sources of TIG, stick,flux cored, and the like welding systems. Moreover, the presentinvention is also applicable with non-welding, high power systems suchas plasma cutters and induction heaters.

Referring to FIGS. 2 and 3, a MIG welding system 10 includes a weldingpower source 12 designed to supply power to a wire feeder 14 through aweld cable 16. The power source is designed to run in one of a number ofmodes including constant voltage (CV) and constant current (CC). Alsoconnected to the power source is a secondary work weld cable 18 thatconnects the power source to a clamp 20 designed to receive cable 18 toworkpiece 22. Also connected to wire feeder 14 is a welding gun or torch24 configured to supply consumable welding wire to a weld. Weldingsystem 10 may further include a gas cylinder 26 connected to wire feeder14 such that shielding gas can be provided through gas hose 28 for theMIG welding process.

Power source 12 is designed to condition raw power supplied from autility line or engine driven power supply and output power usable bythe welding process. As such, power source 12 includes one or moretransformer assemblies (not shown) to condition the raw power. Theoutput of the power source is generally controlled by a controller andassociated operational circuitry that regulates the secondary or outputside of the power conditioning components. As such, the power source maybe initially powered but not provide a welding output until thesecondary power circuit is energized through the closing of a highcurrent DC contactor or other switching assembly. As will be describedin greater detail below, power source 12 is regulated such that asecondary or welding power output is not provided until gun 24 isactivated signaling commencement of the welding process. In this regard,a welding circuit is not created between power source 12 and workpiece22 until gun 24 is activated and is placed in relative proximity withworkpiece 22.

Torch 24 is equipped with a pushbutton trigger 30 that when depressedcauses a transmitter 32 of a controller 34 within wire feeder 14 totransmit command signals to a receiver 36 and power source 12 throughweld cable 16. As such, a separate control cord connecting the wirefeeder and power source to one another is avoided. Further, as will bedescribed in greater detail below, wire feeder 14 is constructed withouta contactor assembly to close the welding circuit. That is, the powernecessary for the wire feeder 14 to supply wire to the weld is notalways present across weld cables 16 and 18. Accordingly, a separatecontactor or switch assembly is not needed in wire feeder 14 to closethe welding circuit. The customary open circuit voltage between a powersource and a wire feeder is then eliminated because a transmitterdisposed within the wire feeder transmits command signals through weldcables 16 and 18 to a receiver 36 disposed within the power source thatis designed to communicate with a controller 38 of the power source suchthat secondary or a welding power output is not provided until thecommand signal is received from the transmitter 32 in the wire feeder.

This construction has a number of advantages. First, the wire feeder 14is designed to be a portable or “suitcase” wire feeder such thatreduction in weight is clearly advantageous. As such, constructing wirefeeder 14 to operate without a separate contactor assembly reduces theoverall weight and size of the wire feeder. Furthermore, the contactorsrequired for high current DC applications can be quite expensive therebyincreasing the overall cost of the wire feeder. Additionally, thecontactor assembly is a maintenance item that may require routinemaintenance for continued proper operation. Therefore, constructing wirefeeder 14 without such a contactor assembly has a number of size- andcost-associated advantages.

Second, incorporation of a transmitter within wire feeder 14 thatcommunicates with a receiver in power source 12 directly through weldcables 16 and 18 eliminates the need for a separate control/power cable.The control cable adds to the complexity, weight, and overall cost ofthe welding system. Additionally, as previously noted, the control cordis typically less durable than the welding cables and, as such, is proneto nicks and snags typically associated with industrial locations.Moreover, incorporating the wire feeder without a separate contactorimproves the overall current capacity of the wire feeder. That is, therating of the contactor assembly within the wire feeder generallydictates the ampacity loads of the wire feeder. Removal of the contactorassembly thereby allows the ampacity loads to be governed by othercomponents of the wire feeder which typically have greater maximumampacity loads than the contactor assembly.

This invention includes both a transmitter and a receiver. Thetransmitter is designed to operate each time the welding gun/electrodeholder trigger is pulled, pressed, or otherwise activated, to start thewire feeder. That is, activation of the trigger causes the wire feederto supply welding wire to a weld. The transmitter is configured totransmit a signal to the receiver via the welding circuit (electrode andwork cables). The signal includes information regarding desiredoperational parameters of the wire feeder and instructs the receiver toset the magnitude of the output of the welding power source (volts oramperes), the mode of the welding power source (CC or CV), and toenergize the output circuit of the welding power source for apredetermined period of time. The transmitter is also configured torepeat a minimum pulse width to provide JOG and PURGE capability. Thatis, when the JOG button is pushed on the wire feeder, the transmitterautomatically repeats the minimum reference command each time the opencircuit voltage of the welding power source falls to zero.

The transmitter is designed to produce a substantially rectangularvoltage pulse that varies in width, preferably, from approximately 10milliseconds to 750 milliseconds. The pulse width may be set by awelding machine operator and represents the desired output of thewelding power source. The transmitter pulse voltage may also be presetby the operator to one of two or more discrete settings (approximately 9volts or 18 volts) to command the welding power source output mode (CCor CV). The transmitter produces one pulse each time the welding guntrigger is activated. The time limits of the minimum and maximumtransmitted pulse width are established so that the LC time constant ofthe welding cable inductance and the high frequency bypass capacitors donot degrade the fidelity of the transmitted signal. Further, it is alsonecessary to complete the data transmission in a short period of time sothat the operator does not experience an appreciable delay in theoperation of the welding-type system when the wire feeder trigger isactivated on the welding gun or torch. The transmitter is alsoconfigured to turn the welding wire feeder ON and OFF after the weldingcircuit is initially energized. When the JOG function is used, thetransmitter is configured to automatically repeat the shortest pulsewidth necessary to energize the output of the power source so the wirefeeder can continuously feed wire when changing wire spools. The PURGEcontrol operates in a manner similar to the JOG control by automaticallyrepeating the minimum pulse width. However, during purging, the gassolenoid in the wire feeder is allowed to operate and the motor of thewire feeder is inhibited or prevented from running.

Referring now to FIG. 4, a circuit illustrating one example ofoperational circuitry for carrying out the transmission functionsheretofore described is shown. When the gun trigger switch S1 is closed,MOSFET Q1 is switched ON, and Q2 is switched OFF. MOSFET Q1 suppliesapproximately 9 volts to the RC timing circuit including active andpassive elements such as capacitors C6 and C7 and inactive element R1,and pulse width control P1. Voltage is also applied to MOSFETs Q9, Q11,and U1. U1 is preferably a CMOS Schmitt-triggered inverter that providesa square waveform to switch MOSFET Q9 ON for a time determined by timingcircuit comprising elements C6, C7, R1, and pulse width control P1, toprovide the output pulse to the welding circuit. The output pulse iseither approximately 8.3 volts (9 volts minus the forward drops ofMOSFETs Q1 and Q9 and diode D3) or approximately 17.3 volts (18 voltsminus the forward drops of MOSFETs Q1 and Q9 and diode D3) depending onthe position of mode select switch S4. When the pulse time is complete,approximately 10 to 750 milliseconds, as set by pulse width control P1,MOSFET Q9 switches OFF, and MOSFET Q10 switches ON. When MOSFET Q10switches ON, the output of optical coupler OC3 switches to an ON stateand the wire feed motor is switched ON. MOSFETs Q10 and Q11 remain in anON state until the gun trigger switch S1 is released. When switch S1 isreleased, MOSFET Q1 switches OFF disconnecting the 9 volt supply fromthe timing and output circuits. MOSFET Q2 switches ON to discharge andreset timing capacitors C6 and C7, MOSFETs Q10 and Q11 switch OFF andoptical coupler OC3 switches the wire feed motor OFF.

Mode selector switch S4 selects the pulse voltage. When switch S4 is inthe CC (constant current) mode, a single 9 volt battery energizes thetransmitter circuit and provides the reference and mode information tothe receiver circuit. When switch S4 is in the CV (constant voltage)mode, a second 9 volt battery is connected in series to provide atransmitted pulse of approximately 17.3 volts.

When the JOG switch S2 is closed, MOSFET Q3 is switched ON which turnsMOSFETs Q4, Q5, Q6, Q7, and Q120N. When MOSFET Q4 switches ON, MOSFET Q1switches ON and MOSFET Q2 switches OFF. When MOSFET Q7 switches ON, itshortens the transmitted pulse width to a minimum value such asapproximately 10 milliseconds. When the short transmitted pulse iscomplete, the power source output is switched ON and optical couplersOC1, OC2, OC3, and OC4 are switched ON due to the presence of an opencircuit voltage via diode D4 and resistors R8, R9, R14, and R15. Opticalcoupler OC1 holds the welding gun trigger pulled as long as MOSFET Q6 isON and open circuit voltage is present. Optical coupler OC2 resetstiming circuit comprising resistor R5 and capacitor C3 while holdingMOSFET Q5 OFF. After approximately 3 seconds, the receiver releases thepower source output contactor if no welding current is detected. Theabsence of open circuit voltage switches optical couplers OC1, OC2, OC3,and OC4 OFF. When optical coupler OC2 releases timing circuit C3 and R5,MOSFET Q5 switches ON repeating the trigger sequence. This results inthe continuous feeding of wire for the purpose of replacing the wirespool. When the JOG switch S2 is released, MOSFETs Q3, Q4, Q5, Q6, Q7,and Q12 switch OFF, releasing the wire feeder trigger. MOSFET Q2switches ON and resets the transmitter timing circuits. When the PURGEswitch S3 is closed, the transmitter operates as described in the JOGmode, however, diode D2 holds MOSFET Q11 in an OFF state therebypreventing optical coupler OC3 from switching the wire feeder ON.

If the transmitter is connected to a welding power source that has anoutput rectifier that uses diodes, the transmitter will only work whenconnected such that the transmitted pulse reverse biases the outputdiodes, (the positive polarity of the transmitter must be connected tothe positive terminal of the welding power source). If the transmitteris connected with the wrong polarity, the diodes in the output rectifierof the welding power source will be forward biased by the transmittedpulse and shunt the pulse through the transformer secondary winding. Ifthis occurs, the receiver cannot detect the pulse. Therefore, thetransmitter circuit includes a two-pole two-throw toggle switchconnected to change the polarity connection of the transmitter when thewelding polarity connection to the wire feeder is changed.

If the transmitter is connected to the welding circuit with the wrongpolarity and the power source secondary contactor control is ON so thewelding circuit is energized, diode D3 will be forward biased howeverthe body drain diode (intrinsic diode) in Q9 will block the voltage toprotect the transmitter circuit. Diode D5 will be forward biased andoptical coupler OC5 will maintain Q9 OFF in the event that the TRIGGER,JOG, or PURGE switches are activated.

The voltage sensing receiver section of the remote control is configuredto detect both start and reference commands from the transmitter throughthe weld cables. The receiver switches ON the secondary power output ofthe power source and sets the magnitude of the secondary power sourceoutput. The receiver includes a current sensing circuit that detects arccurrent and maintains power source secondary contactor in an ON statewhile welding. A mode sensing circuit detects a mode command and setsthe welding power source output to either a CV or a CC. These aspects ofthe receiver and an example of operational circuitry are describedbelow.

Referring now to FIG. 5, a voltage feedback signal is present at RC1,pin 3 that is provided the welding power source and represents thevoltage present in the welding circuit (electrode to work). The voltagefeedback signal is scaled so that 10 volts electrode to workpiece equalsa 1 volt feedback signal. When the transmitter sends a pulse of 9 or 18volts, the input signal at RC1 (pin 3) is 0.9 or 1.8 volts respectively.Amplifier A1 (pins 1, 2, and 3) increases the input signal with a gainof approximately 11. The voltage signal is then applied to voltagecomparator A1 (pins 5, 6, and 7). Comparator A1 recognizes any inputvoltage greater than approximately 6.4 volts (set by bias resistors R13and R14) as a command pulse from the transmitter, and switches itsoutput from −15 volts to +15 volts for the duration of the transmittedpulse. The positive transition of comparator A1 (pin 7) is coupledthrough differentiator circuit C11 and R19 to Schmitt-triggeredinverters U1 (pins 10 and 11, and 12 and 13). U1 (pin 12) provides areset pulse to pre-settable cascaded binary counters U4 and U5 that setsthe outputs of U4 and U5 to all zeros. Cascaded pre-settable binarycounters U4 and U5 are configured to count up when clocked. When A1 (pin7) switches to +15 volts, blocking oscillator circuit U2 (pins 4, 5, 6,8, 9, 10, C12, and R20) switches on at approximately 330 Hz. Theblocking oscillator indexes cascaded counters U4 and U5 for the durationof the transmitted pulse. Diode D8 provides a blocking oscillatorinhibit signal to stop the counters from advancing if the counters reachtheir maximum binary number of 255 before the transmitted pulse iscomplete. This prevents the counters from resetting to zero iftolerances in oscillator frequency and transmitter pulse widthaccumulate so that the counter reaches 255 before the end of thetransmitted pulse. The digital output of counters U4 and U5 is convertedto an analog voltage signal by resistors R21 through R31 and currentsumming amplifiers A2 (pins 1, 2, 3, and 5, 6, 7). The analog voltagesignal present at A2 (pin 7) is the output reference command for thewelding power source.

When the output of comparator A1 (pin 7) switches to +15 volts, theoutput of NAND gate U2 (pin 3) switches to logic level zero (ground),discharging timing capacitor C9. At the completion of the transmittedpulse, the output of NAND gate U2 (pin 3) switches to +15 volts. Thepositive transition of NAND gate U2 (pin 3) is coupled throughdifferentiator circuit C9 and R9 to the input of cascadedSchmitt-triggered inverters U1 (pins 1, 2, 3, and 4) that function tobuffer and shape the timing pulse from capacitor C9. The output ofinverter U1 (pin 4) is coupled through diodes D4 and D9 to switch ONMOSFET transistors Q1 and Q2, respectively. MOSFET Q1 switches ONoptical-coupler OC1. The output of optical coupler OC1 switches thewelding power source secondary contactor ON for the duration of thetiming pulse set by elements C9 and R9 (approximately 3 to 5 seconds).MOSFET transistor Q2 switches ON when the welding power source secondarycontactor is energized by optical coupler OC1 to inhibit the voltagesensing circuit comparator A1 (pins 5, 6, and 7) from responding to thevoltage present while welding.

Capacitor C14, resistor R33, NAND gate U2 (pins 11, 12, and 13), anddiode D10 provide a blanking pulse to the voltage sensing circuit in thereceiver when the power source is switched ON. This prevents thereceiver from improperly switching ON the power source secondarycontactor when the power source is initially switched ON and the logiclevel power supplies are coming up.

Comparator A2 (pins 12, 13, and 14) provides an enable/inhibit signal tothe current sensing circuit. Comparator A2 (pins 12, 13, and 14)compares the voltage feedback signal at RC1 (pin 3) to a bias voltageset by resistors R40, R41, and R43. R43 sets the bias signal as afunction of the welding power source output voltage command present atRC1 (pin 6). Comparator A2 (pins 12, 13, and 14) prevents the electrodefrom melting back to the contact tube in the welding gun when thetrigger is released. When the voltage feedback exceeds the bias signalat A2 (pin 12), A2 (pin 14) switches to 15 volts and inhibits thecurrent sense signal at U3 (pin 11).

When the welding power source secondary contactor switches ON, thewelding circuit is energized providing voltage to the wire feeder andwelding circuit. The wire feeder can operate for the 3 to 5 secondperiod set by timing circuit C9, R9. If during that time, no arc isestablished, MOSFET transistor Q1 switches OFF and turns OFF the weldingpower source secondary contactor. Alternatively, if a welding arc isestablished during the 3 to 5 seconds of initial time, a currentfeedback signal that is scaled so that 100 amps of welding currentequals approximately 1 volt of feedback is present at RC1 (pin 5). Inputbuffer amplifier A1 (pins 8, 9, and 10) increases the signal amplitudewith a gain of approximately 32. The output of current sensing circuitbuffer A1 (pin 8) is applied to the input of comparator A1 (pins 12, 13,and 14). Comparator A1 (pins 12, 13, and 14) is biased to switch atapproximately 7.5 volts by resistors R7 and R8. The 7.5 volt biascorresponds to approximately 25 amperes of welding current. Therefore,any welding current value greater than 25 amperes will hold the output(pin 14) of comparator A1 at +15 volts. Resistor R38 protects the inputto inverter U1 (pin 5) when (pin 14) of A1 is at negative 15 volts. Whenarc current is greater than 25 amperes and (pin 14) of comparator A2 ispositive, (pin 11) of gate U3 switches negative. The output of gate U3(pin 11) is coupled through resistor R34, diode D11, and resistor R10 totiming capacitor C9 to provide a parallel impedance to timing resistorR9. This reduces the timing pulse from the voltage sensing circuit whenarc current greater than 25 amperes is present. The output of gate U3(pin 11) is also connected to the input of inverter U1 (pin 9). When(pin 14) of comparator A1 switches to +15 volts, (pin 8) of inverter U1also switches to +15 volts. The output of inverter U1 (pin 8) is coupledto the gate of MOSFET transistor Q1 through diode D5. When MOSFET Q1switches ON, its output signal is coupled through optical isolator OC1to switch ON and maintain the secondary contactor in the welding powersource in the ON state. Resistor R11 and capacitor C10 provide a brieftime delay, (10 to 20 milliseconds) to maintain MOSFET Q1 ON in theevent of a brief arc outage while welding.

Referring again to FIG. 5, the receiver circuitry includes a modesensing circuit. The mode command is established by amplitudemodulation. The mode selector switch in the transmitter selects a single9 volt battery for the CC mode or two series connected 9 volt batteriesfor the CV mode. Receiver voltage comparator A2 (pins 8, 9, and 10)compares the transmitted voltage pulse from buffer amplifier A1 (pins 1,2, and 3), to the voltage reference set by bias resistors R35 and R36,approximately 11.75 volts. If the detected pulse is less than 11.75volts, the output of comparator A2 (pins 8, 9, and 10) is negative 15volts. Diode D12 blocks the negative voltage at (pin 8) of A2 from theinput of NAND gate U3 (pins 1 and 2). Resistor R37 holds the input ofgate U3 (pins 1 and 2) at logic level zero (ground) and U3 output (pin3) is maintained at +15 volts. When the transmitted voltage pulse isbeing received, the output of gate U2 (pin 3) is at logic level zero.Output (pin 3) of gate U2 is coupled to input (pin 9) of gate U3 throughresistor R39. With logic level zero at (pin 9) of gate U3, output (pin10) of U3 is held at logic level 1 (+15 volts). Output (pin 10) of gateU3 holds input (pin 6) of gate U3 at logic level 1. With both (pins 5and 6) of gate U3 at logic level 1, output (pin 4) of gate U3 is held atlogic level zero. (Pin 4) of gate U3 holds input (pin 8) of gate U3 atlogic level zero and maintains U3 (pin 10) at logic level 1. The output(pin 4) of gate U3 also provides a logic level zero to RC1 (pin 4). Alogic level zero at RC1 (pin 4) places the welding power source in theCC mode.

If the transmitted pulse voltage is greater than 11.75 volts, comparatorA2 (pin 8) switches to +15 volts. This holds input (pins 1 and 2) ofgate U3 at logic level 1 and output (pin 3) at logic level zero. Theoutput (pin 3) of gate U3 holds input (pin 5) of gate U3 at logic levelzero and output (pin 4) at logic level 1. Output (pin 4) of gate U3holds input (pin 8) of gate U3 at logic level 1. When the transmittedpulse is complete, output (pin 3) of gate U2 switches to logic level 1and holds input (pin 9) of gate U3 at logic level 1. With logic level 1at (pins 8 and 9) of gate U3, output (pin 10) of gate U3 and input (pin6) of gate U3 are held at logic level zero maintaining logic level 1 onoutput (pin 4) of gate U3 and RC1 (pin 4). A logic level 1 signal at(pin 4) of RC1 places the welding power source in the CV mode. Timingcircuit R37 and C18 maintains the input logic level 1 at (pins 1 and 2)of gate U3 while gate U2 (pin 3) switches to logic level 1 at thecompletion of the transmitted pulse.

As stated above, the present invention is also applicable with non-MIGwelding systems such as TIG and stick welders. Further, theaforedescribed circuitry may be implemented to automatically adjust theoutput of a power source to compensate for losses that occur across weldcables. That is, in some manufacturing and/or industrial settings, theweld is a relatively great distance from the power source. As such, theweld cables may be dozens to over a hundred feet in length. This weldcable length results in losses from the output terminal of the powersource to the weld. Simply, the voltage at the output terminals of thepower source (where the weld cable is connected to the power source) maybe significantly more than the voltage across the weld. Accordingly, thepresent invention may be used to transmit a voltage feedback signal atthe weld to the power source whereupon a controller in the power sourcecompares the voltage at the terminal to the voltage at the weld andadjusts the voltage at the terminal such that after the lossesexperienced across the weld cables, the voltage at the weld is at thelevel requested by the user.

Therefore, in accordance with one embodiment of the present invention, awelding system includes a power source having a controller to regulatewelding operation. An electrode holder having a trigger is configured tohold an electrode in relative proximity to a workpiece such that awelding arc is created between the electrode and the workpiece. Thesystem also includes a transmitter configured to detect activation ofthe trigger and, responsive thereto, transmit a signal indicative ofdesired welding operation through weld cables. A receiver is providedremotely from the transmitter and is configured to receive the signaland instruct the controller of the power source according to the desiredwelding operation.

In accordance with another embodiment of the present invention, awelding system includes a power source configured to condition raw powerand supply a power usable during a welding process. A wire feeder isconfigured to receive the power from the power source and supply aconsumable electrode to a weld. The wire feeder includes a torchconnected thereto and a transmitter configured to detect activation ofthe torch and transmit a signal to a receiver of the power sourceindicating activation of the torch. The welding system further includesa welding cable connecting the power source and the wire feeder to oneanother such that the signal is transmittable thereacross from thetransmitter to the receiver. The system is constructed such that avoltage is not created across the weld cable until the transmittertransmits a signal to the receiver signaling that the torch has beenactivated.

According to another embodiment of the present invention, a method ofremotely controlling a power source for a welder includes the step ofdetecting activation of a triggering mechanism of a welding-type torchto initiate a welding-type process. The method further includes the stepof transmitting a signal indicative of desired operational parameters ofthe power source through weld cables connected to the power source and aworkpiece, automatically upon activation of the triggering mechanism.The transmitted signal is then received remotely from the triggeringmechanism whereupon the power source is controlled in accordance withdata embodied in the signal transmitted through the weld cables.

In accordance with yet a further embodiment of the present invention, akit to retrofit a welder and wire feeder system is provided. The kitincludes a transmitter to be disposed within a wire feeder andconfigured to detect activation of a welding torch. The kit alsoincludes a receiver to be disposed within a power source andelectrically connected to the transmitter through the weld cables. Acontroller is provided to regulate operation of the power source suchthan an open circuit voltage is not created across the weld cables untilan energized secondary voltage command signal is received by thereceiver from the transmitter.

The present invention has been described in terms of the preferredembodiment, and it is recognized that equivalents, alternatives, andmodifications, aside from those expressly stated, are possible andwithin the scope of the appending claims.

1. A welding system comprising: a power source having a controller toregulate welding operation; an electrode holder configured to hold anelectrode in relative proximity to a workpiece such that a welding arcis created between the electrode and the workpiece, the electrode holderhaving a trigger that when activated commences a welding process; atransmitter configured to detect activation of the trigger andresponsive thereto transmit a signal indicative of desired weldingoperation through at least a weld cable; and a receiver remote from thetransmitter and configured to receive the signal and instruct thecontroller to regulate the power source according to the desired weldingoperation.
 2. The welding system of claim 1 wherein the transmitter isfurther configured to transmit the signal through a pair of weld cablesand the electrode holder.
 3. The welding system of claim 1 wherein thedesired welding operation includes at least one of a magnitude of powersource output and a power source mode.
 4. The welding system of claim 3wherein power source mode includes one of constant current and constantvoltage.
 5. The welding system of claim 1 wherein the signal causes thereceiver to further instruct the controller to energize an outputcircuit of the power source upon activation of the trigger.
 6. Thewelding system of claim 1 wherein the transmitter is further configuredto produce a substantially rectangular voltage pulse of variable width.7. The welding system of claim 6 wherein the width of the pulse isindicative of desired output of the power source.
 8. The welding systemof claim 6 wherein the transmitter is further configured to produce onepulse each time the trigger is activated.
 9. The welding system of claim1 further comprising a wire feeder connected to the electrode holder andconnected to the power source via the weld cable, wherein thetransmitter is further configured to output a signal that causes thewire feeder to automatically supply consumable wire to the weld when awelding circuit is created between the electrode and the workpiece. 10.The welding system of claim 9 wherein the wire feeder includes aportable wire feeder.
 11. The welding system of claim 1 wherein thecontroller includes voltage sensing circuitry designed to switch onpower source output when the electrode and workpiece form a closedcircuit and current sensing circuitry designed to detect arc current andmaintain activation of the power source output when an arc current ispresent.
 12. The welding system of claim 1 configured for at least oneof a MIG welding process, a TIG welding process, a flux cored weldingprocess, a stick welding process, a submerged arc welding process, and agouging process.
 13. A welding system comprising: a power sourceconfigured to condition raw power and supply a power usable during awelding process; a wire feeder configured to receive the power from thepower source and supply a consumable electrode to a weld, the wirefeeder having a torch connected thereto and a transmitter configured todetect activation of the torch and transmit a signal to a receiver ofthe power source indicative of activation of the torch; and a weldingcable connecting the power source and the wire feeder such that thesignal is transmittable thereacross from the transmitter to thereceiver, the power source and wire feeder connected such that a voltageis not created across the weld cables until the transmitter transmits asignal to the receiver signaling that the torch has been activated. 14.The welding system of claim 13 configured to not have an open circuitvoltage across the welding cables when the power source is powered onand the torch is not activated.
 15. The welding system of claim 13wherein the power source further includes circuitry such that asecondary power is not output until activation of the torch.
 16. Thewelding system of claim 15 wherein the wire feeder is further configuredwithout a contactor to close a circuit between a secondary power outputof the power source and the torch.
 17. The welding system of claim 13wherein the transmitter is further configured to transmit the signal tothe receiver encoded with information regarding desired operationalparameters of the power source.
 18. The welding system of claim 17wherein the desired operational parameters include at least one of powersource output magnitude, power source welding mode, purging, andjogging.
 19. A method of remotely controlling a power source for weldingcomprising the steps of: detecting activation of a triggering mechanismof a welding-type torch to initiate a welding-type process; transmittinga signal indicative of desired operational parameters of the powersource through at least a weld cable automatically upon activation ofthe trigger; receiving the signal remotely from the trigger mechanism;and controlling the power source in accordance with data embodied in thesignal transmitted through at least the weld cable.
 20. The method ofclaim 19 further comprising the step of preventing an open circuitvoltage between the welding-type torch and the power source duringnon-activation of the trigger.
 21. The method of claim 20 furthercomprising the step of only allowing current flow between the powersource and the welding-type torch when the trigger is activated.
 22. Themethod of claim 19 further comprising the step of transmitting a pulsedsignal upon activation of the trigger through the weld cable, the pulsedsignal having a width indicative of a desired secondary output of thepower source.
 23. The method of claim 19 further comprising the step ofreceiving feedback of a voltage at a weld and automatically adjustingoutput of the power source based on the feedback.
 24. The method ofclaim 23 further comprising the step of adjusting output of the powersource to accommodate losses that occur across the weld cable betweenthe power source and the welding arc.
 25. A kit to retrofit a welder andwire feeder system, the kit comprising: a transmitter to be disposedwithin a wire feeder and detect activation of a welding torch; areceiver to be disposed within a power source and electrically connectedto the transmitter through weld cables; and a controller to regulateoperation of the power source such that a voltage is not created acrossthe weld cables until an energized secondary voltage command signal isreceived by the receiver from the transmitter.